1. Field of the Invention
The present invention relates to an image capturing device and a lens actuating device and a lens actuating method thereof, in particular to the image capturing device and the lens actuating device and method thereof that use a microcontroller to control a single motor by different instructions to operate at different rotating speeds for a focus or zoom function.
2. Description of the Related Art
At present, most digital still cameras (DSC) available in the market come with zoom and focus functions which are driven and controlled by a DC motor and a step motor respectively, or by a single step motor. There are not many cameras that use a single DC motor to control both zoom and focus functions in the market.
In order to use two motors comprising a DC motor and a step motor for the zoom and focus controls, two sets of control circuits will be required, and the construction cost of the DSC will be increased, and the DC motor can only be used for controlling a change of speeds for the zooming. When a single step motor is used to achieve the zoom and focus controls, the control of rotating speeds will no longer be a concern and a controller is generally used to issue an instruction to control the zooming and focusing precisely. However, the drop current released from the step motor is higher than that of the DC motor. When both zooming and focusing are controlled by the step motor, the battery of the DSC will be exhausted quickly, such that the camera not only fails to meet maximum number of photos taken requirements, but also fails to comply with the power saving requirements or meet the user requirements. When the single DC motor is used for the zooming and focusing functions and only one rotating speed is used for executing the zoom and focus motions, the efficiency of use is too low.
Therefore, the present invention overcomes the aforementioned problems by using a single motor to control the zoom and focus motions, and controls the rotating speed to improve the overall performance.